The development of high energy battery systems requires the compatibility of an electrolyte possessing desirable electrochemical properties with highly reactive, high energy density anode and cathode materials, such as lithium, sodium, FeS2 and the like.
While the theoretical energy, i.e. the electrical energy potentially available from a selected anode-cathode couple is relatively easy to calculate, there is a need to choose an electrolyte for such couple that permits the actual energy produced by an assembled battery to approach the theoretical energy. The problem usually encountered is that it is practically impossible to predict in advance how well, if at all, an electrolyte will function with a selected couple. Although a cell must be considered as a unit having three parts, a cathode, an anode and an electrolyte, and it is to be understood that the parts of one cell are not predictably interchangeable with parts of another cell to produce an efficient and workable cell. It has been realized that the separator, in conjunction with the electrolyte, can play an important part in the performance characteristics of a cell.
Many electrochemical systems can function in various environments when they are freshly produced. However, when cell systems are stored for long periods of time at high temperatures, their impedance characteristics can become altered to render the electrochemical systems unsuitable for some consumer applications. A specific high rate application of a cell is its use in cameras. Although cells can function under normal conditions, many cells may exhibit high voltage drop under high drain rates as exemplified in flash cameras.
There exists a need to provide an electrolyte solution and separator combination for use in an electrochemical cell to provide lower overall cell impedance to substantially increase cell performance.